The present invention relates to the field of products made of tissue for sanitary or domestic use and is aimed in particular at products in rolls such as rolls of bathroom tissue (or sanitary paper) and similar rolls.
The subject of the invention is a roll consisting of articles based on a (or essentially made of a) fibrous cellulosic product. More particularly, and according to a preferred embodiment, the subject of the invention is a roll of which certain sheets, and again more preferably, of which each sheet comprising it, has a single pattern completely included in the format of the sheet(s), that is to say that it is not cut by one or more of the four edges that delimit the sheet (usually of rectangular shape or surface area).
In a general manner, products of the above type are already known packaged in roll form. In these rolls, the sheets of product to be dispensed are usually rolled on a central mandrel of cylindrical section made of cardboard or similar product. In the field concerned, the rolled sheets of value to the user are conventionally made from fibrous cellulosic products of (or mostly of) tissue and assembled in the form of one or more superposed connected plies (stratified products or of the “sandwich” type) that follow one another in single file on the roll, the sheets being separated from one another, in the direction perpendicular to the direction of unrolling of the sheets by perforated or pre-cut lines making it possible to tear off or detach one or more sheets from the roll.
In the case of rolls of multi-ply sheets, the various superposed plies of the same size are, depending on the intended use of the sheet and/or the requirements imposed by the desires of the consumer and/or the technical production constraints, more or less strongly connected together using various techniques of assembling the said plies.
Most frequently, the plies in a multi-ply product made essentially of tissue are joined by applying an adhesive between the said plies. The bonding is carried out by means of any adhesive product generally used in the field of sanitary and domestic papers to join plies together such as, for example, a polyvinyl alcohol in solution in an aqueous medium. This joining by bonding may be combined with another type, just as conventional, of joining plies that is purely mechanical and that consists in locally deforming, by crushing, the plies to be connected so that the latter, nested in one another under the pressure of a cylinder, are held together once the joining operation has ended.
In the case of bonding, the adhesive has hitherto been deposited uniformly over the whole surface area of the plies of the rolled product. Since the deposition of the adhesive is associated with the embossing pattern, this requires an embossing pattern that covers the whole surface area of the product.
The patterns currently used are therefore of relatively small size and repeated a certain number of times in the machine direction and cross direction of each sheet, usually with at least two similar or identical patterns per sheet of paper, for example bathroom tissue.
This creates a continuous succession of embossed patterns all along the sheets that follow one another when the product is unrolled from the roll, the said patterns being cut in a more or less random fashion when they encounter one of the lateral edges of the ribbon formed by the succession of the sheets coupled together when they are unrolled in the machine direction and when they encounter a transverse edge that forms in the cross direction when the user detaches a sheet from the roll and/or two sheets that follow one another. This is particularly critical and unattractive when the patterns are relatively large in their surface area relative to the dimensions of the sheet since these cuts break the pattern and may, by reason of the geometric shape of certain patterns, cause weakened zones to appear where the connections are, likewise due to the cutting of the pattern, weaker than what would be the case in a complete uncut pattern.
Another disadvantage associated with the abovementioned type of joining by bonding consists in a stiffening of the sheet of paper (because of the adhesive) and hence a more difficult and more tricky rolling. Furthermore, with a mechanical treatment of the embossing type, an “inside-out” effect is noted due to the protrusions particularly in the zone of use, that is to say in the central zone of the sheet of paper and an accelerated penetration of the paper by a liquid due to an effect called “tent canvas” effect at the aforementioned joining protrusions.
Finally, the strength at the embossing patterns is weakened in the zone of use due mainly to the destruction of the fibres.
These disadvantages are particularly important when the rolled paper is bathroom tissue or similar paper of which the main qualities sought are above all flexibility, softness, tear-strength (in particular when wet) and appearance.
There is therefore a real need to be able to offer the consumer a roll of paper of this type that combines both a presentable appearance, preferably original and able to be modified at will, with properties of strength, flexibility and softness at least equivalent to those of the known rolled products where the patterns are repeated at frequencies that can be very high and that are cut at the edges of the sheets in the rolled state or detached from the roll.
An advantage of the present invention is to alleviate at least certain of these disadvantages.